Eighty-five pregnant problem drinkers were given intensive counselling throughout gestation to persuade them to reduce or stop their alcohol intake. Nevertheless, 7% of their blood specimens collected at follow-up visits contained ethanol. Fifty-five women (65%) were able to reduce their alcohol consumption by at least 50%. Alcohol abuse was associated in a dose-dependent manner with fetal growth retardation detectable by ultrasonography from 27 weeks gestation. Twenty infants (24%) had a complete fetal alcohol syndrome and 22 (26%) had some features of 'fetal alcohol effects' (FAE). In addition, the rate of structural malformations was high (13%). Of the women with continuous alcohol abuse 89% gave birth to infants with at least one feature of FAE compared with only 40% of those who decreased their alcohol consumption.